The airport’s current peak demand is about 14 megawatts, so the airport will be able to use the onsite generation facilities as its primary power source, marking the first time a microgrid has been used to power an entire airport, according to the project team. It will remain connected to the existing electrical grid for optional emergency backup power, if needed.

Tom Woodrow, vice president of engineering at the airport, says the idea to create a microgrid was first pitched by a private developer in 2017. As the airport team was preparing public advertising documents to explore the concept under its procurement requirements in December 2017, Atlanta’s Hartsfield-Jackson International suffered a crippling 11-hour power outage that forced the cancellation of nearly 1,400 flights and cost its air carriers more than $100 million in losses.

That’s when the opportunity to build power supply resiliency into its facilities with an independent microgrid became a primary impetus for the project. “That [outage] was exactly what we don’t want to happen to us,” Woodrow recalls. “The value of the lights not going out is priceless. You can’t really quantify that.”

Priceless Benefits

While the value of its benefits may be priceless, the project comes with a price tag of around $30 million, Woodrow says. In 2018, the airport signed a deal with Peoples Natural Gas, which agreed to design, build, finance, operate and maintain the microgrid. Under the 20-year deal, the airport will purchase power generated by the microgrid from Peoples at a below-market rate. Woodrow says that could save the airport $500,000 in the first year. After the 20-year term, the airport has the option to sign a new agreement with Peoples, bring in a different owner to operate the grid or buy the grid itself.

LLI Engineering leads the project’s design efforts; PJ Dick is the general contractor. Other team members include CNX Resources—which leases the gas wells on the property and will help supply the future plant—and IMG Energy Solutions, which leads development of the solar component with contractor EIS Solar.

For the deal to make financial sense, many factors had to line up just right, says Jeff Nehr, Peoples vice president of business development. A critical part of the project was connecting the microgrid to the airport’s two substations. Fortunately, when the airport was renovated in the 1990s, extra underground conduit was built into the system. That allowed the microgrid team to make the connection without the added challenge and expense of having to dig under or around existing runways, a taxiway and buildings.

“You can chalk that up to planning on the airport’s part,” Nehr says. “If it wasn’t for their forethought to create extra conduit, we couldn’t do this.”

As the team worked through more detailed planning, several other serendipitous factors fell into place, says Jamie White, president of LLI Engineering. The original site for the natural gas plant had to be changed because it would have conflicted with plans in the works for a separate $1.1-billion modernization program at the airport (see Pittsburgh International Airport Ready to Restart $1B Terminal Modernization). The team conducted numerous studies for factors such as lighting, glare, thermal uplift from the generator stacks, noise, emissions and other environmental considerations. The team settled on a one-acre section of an unused parking lot that already was graded and had good soils, White says. One 5kV cable that ran under the site had to be relocated.

Two of the site’s advantages are that it offers access to the open conduit and is roughly 400 ft away from an existing natural gas main. Regarding workers’ access during construction, the site is on airport property but outside of the Federal Aviation Administration secured area, so there are fewer complications. Crews began sitework in July 2020.

For the plant itself, the team chose to use five Jenbacher natural gas engine modules, each with a 4.3-megawatt capacity. Each unit is divided into three 55-ft-long pieces that vary in size but average around 10 ft wide.  The crews used a 400-ton crane to pick the module pieces. When assembled, the system creates a combined unit that is about 20 ft wide, 30 ft tall and 55 ft long. The modules were supplied by Northeast Energy Systems, which was responsible for transporting the modules from the fabrication plant in Austria to the airport. After arrival at a port in New Jersey, each unit required six trucks—three for each of the main pieces and three to carry other required components. Once they were at the airport, contractor PJ Dick was responsible for transporting them through the airport to the site. That journey included having to travel through a taxiway underpass.

For foundations, crews installed 90 geopiers to support a concrete mat. The team originally had proposed enclosing the generators in a building, but White says the enclosures for the modules are robust enough to remain outdoors. The enclosures also include isolation pads to reduce vibration and noise, so no additional mitigation measures were required.

After the pieces are staged, the basic assembly of each unit can take up to two weeks, followed by several more weeks of electrical and piping work.

Home Stretch

With the plant nearly complete, the team at press time was shifting its attention to connecting it to the airport. White says that is the project’s most complex portion. The original plan was to connect to both the airport’s midfield substation and hangar substation, which are currently fed by power utility Duquesne Light. White says, “The problem is the hangar substation is fed from a different Duquesne Light substation from one feeding the airport, so they are on different frequencies.”  

The solution was to install a Kirk Key interlock system that keeps the power sources separated but allows for a manual connection from one to the other, if needed.

“If we have a total outage [at the plant], you physically change the breaker settings through the Kirk Key interlock system and then that is fed by the Duquesne system,” White adds.

White says a transformer is also required at the midfield station. “Because we were so far from the midfield terminal and we were restricted by the existing conduits in between, we decided to transmit our electricity to the midfield at 13.8kv, where the airport is 4,160v,” he says. “When we bring that over, we have to transform down.”

As part of its terminal modernization plan, the airport also decided to upgrade its switchgear at the midfield terminal. “With that change out of the gear, we had to reengineer how to connect to that system,” he says.

Installation of the solar portion of the project started in January. It is expected to deliver 9,390 panels on eight acres when completed this summer. Although all under one agreement with the airport, the 3.5-megawatt solar facility will be built, operated and maintained by IMG Energy Solutions.

The facility will not connect to the natural gas plant’s grid. Instead, it will feed directly into the Duquesne Light grid and help power other buildings surrounding the airport. Because the two facilities have the capacity to deliver more power than the airport currently needs, an asset manager will be tasked with selling back unused power to Duquesne Light.

With the project’s completion on the horizon, Nehr says he hopes it can serve as an example for other airports that are considering resilient power sources. Smaller microgrids are in place at JFK International  Airport and Detroit Metro Airport. In addition, Denver International Airport recently completed a microgrid study. Nehr says, “If it can offer some cost savings along with resiliency, it’s a good option for airports.”